Problem: $ { \left[\begin{array}{r}{-1} \\ {-1} \\ {3}\end{array}\right]+\left[\begin{array}{r}{0} \\ {0} \\ {0}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{r}{-1}+{0} \\ {-1}+{0} \\ {3}+{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{-1} \\ {-1} \\ {3}\end{array}\right]}$